Lewis is out after picking up an impact injury against Dagenham, believed to be related to a dead leg, while Brown hasn’t been able to shake a virus which kept him out for most of the latter stages of pre-season.

Jabo Ibehre and Brad Halliday are the only other injury concerns ahead of the U’s League Two opener.

Striker Ibehre was substituted just before the hour mark against Bishop’s Stortford last Saturday after feeling tightness, while Halliday hasn’t featured since the Chelmsford game.

Halliday was involved in the warm-up against Stortford, however, while also taking part in the U’s open day.

A decision will be made on the pair on Friday and even though both have missed game time and training, Dunne is confident that, should they pass a fitness test, they’ll be fine to play.

“I think they’ll be okay,” he said. "They [the squad] all came back in a real healthy shape.

“I think trying to get Jabo through [Friday’s] session is just based on what happened last week, so he’s only missed one week [of training] while Brad is a fit lad anyway and he’s only missed since the Chelmsford match .

"They’ve been working with Mikey [Burroughs, head of medical] and Matt [Walker, head of performance] trying to get themselves back to fitness.

“We’ll just have to see if tomorrow’s [Port Vale is] a touch too early but if it is, it is and we’ll deal with the next week as it comes.”